What is Dolby Atmos?

Posted on November 23, 2023 by Glen

And why should I care? Isn’t good old fashioned ‘stereo’ good enough for my aging ears, you might ask?

Well, according to this USA Today article Dolby Atmos is “a three-dimensional sound format that aims to be as impressive for your ears as Dolby Vision HDR is for your eyes” and it “is the future of cinematic audio—and maybe even music.” Sounds impressive, right?

What is Dolby Atmos? (source)

“According to Dolby Laboratories, Dolby Atmos grants two key advantages over a traditional surround sound setup:

  • The addition of height audio creates “a full audio atmosphere, realistically depicting objects moving overhead.”
  • Sounds can be precisely placed within the aural space around the room, regardless of your speaker setup, with object-based audio.

With speaker-based formats, sound is always mixed to speaker channels, but object-based audio with Dolby Atmos allows each sound (or audio object) to be mixed with metadata that includes its exact placement in space. The Dolby Atmos decoder knows how many speakers are in a room and their locations. It directs the audio object in real time to the proper combination of speakers so it sounds from the correct spot in your room. Dolby Atmos allows for up to 118 of these audio objects to be happening simultaneously.

This allows sound engineers mixing in Dolby Atmos the freedom to orient any recorded sound—from a spaceship to a mosquito—virtually anywhere along the horizontal or vertical planes without the worry of it matching a specific speaker configuration or layout.”

Let’s talk about speakers…

Understanding how Dolby Atmos works requires some discussion about speaker configurations. If you have been shopping for speakers lately you might have seen numbers like 5.1.2, 7.1.4, 5.1, and so on popping up. These numbers represent different speaker-channel configurations.

The first number, using the example of 5.1.2, is a count of the conventional speakers/channels within the setup. For example, the “5” in 5.1.2 refers to 5 different speaker channels, usually including left, center, and right speaker channels up front, as well as left and right surround channels set behind the listening position.

The second number refers to subwoofers. It’s almost always .1, though some setups will employ multiple subwoofers for extra accuracy and power.

The last number—the 2 in 5.1.2 refers to the height channels, which are integral to creating the added immersion of a 3D-audio configuration such as Dolby Atmos. Home Dolby Atmos configurations use either 2 or 4 height speakers.

If I don’t want all those speakers, can I use a soundbar and still get Dolby Atmos?

Apparently you can. Samsung’s 11.1.4-channel HW-Q990C soundbar is an example of an advanced Dolby Atmos soundbar, offering 11 conventional speaker channels, 1 wireless subwoofer, and 4 upward-firing (or height-channel) speaker drivers along with multiple side-firing drivers. But it costs $1200 – $1400, depending on where you shop.

The JBL Bar 700 soundbar (with subwoofer) sells for only $600 on Amazon. It gets excellent reviews for space-constrained applications and supports the more immersive (Dolby Atmos) experience should you opt to detach the ends of the speaker and add them as rear-channel effects behind your head.

The Vizio M-series 5.1.2 Dolby Atmos soundbar is another to consider. Depending on the model you chose, this soundbar costs $350 to $500 on Amazon.

And if having speakers scattered about isn’t a problem?

In this case, you can pick up a Klipsch Reference Cinema Dolby Atmos 5.1.4 System for a mere $330 on Amazon.

However, you’re also going to need to purchase a receiver that supports Dolby Atmos. Here are some that fit the bill:

The other thing to keep in mind when taking the speaker route is cables – lots of cables! For me, if I can got Dolby Atmos without cables running across my living room, I would be a much happier person.

What else do I need to know about Dolby Atmos?

First, there are two Dolby Atmos formats – Dolby TrueHD and Dolby Digital Plus. Dolby TrueHD is the lossless/uncompressed format, while Dolby Digital Plus is the lossy/compressed (lower qualit) format. Dolby TrueHD required a lot more data so it’s generally confined to physical or downloaded media such as Blu-ray discs or premium video games. Dolby Digital Plus is more compact and is generally utilized in Dolby Atmos-compatible streaming services like Disney+, Netflix, Amazon Prime Video, and others.

So now I have another question. Will my Roku Ultra, Apple TV, Fire TV, Google TV and other streaming devices be able to pass Dolby Atmos to my speakers? The answer is “maybe”. I recommend upgrading your Roku to the Roku Ultra for about $70. This device supports Dolby Vision (picture) and Dolby Atmos (sound). Also, you’ll most likely want to plug the Ultra’s HDMI cable directly into the Dolby Atmos compatible receiver or soundbar for proper decoding since older TVs lack the hardware needed to support decoding of the audio data.

To quote the USA Today article once again, there’s this caveat regarding newer TVs and ARC:

“On the other hand, most newer TVs (usually 2017 or later) can decode Dolby Digital Plus, allowing you to stream Dolby Atmos content directly from your TV and pass the audio down to your soundbar or receiver over HDMI ARC (Audio Return Channel) connection. (An optical cable cannot transfer Dolby Atmos, so you’ll have to connect your audio system with an HDMI cable.)

There is an exception, in that some newer TVs (from around 2019 or later) offer an advanced version of HDMI ARC called HDMI eARC. With eARC, even if your TV can’t decode high-resolution audio data such as Dolby TrueHD, it can pass the unaltered information from a connected Blu-ray player or other device directly to a sound system via HDMI eARC, allowing the audio device to decode the audio and send it to your ears.

It is important to note that, in order to utilize HDMI eARC, it must be supported by both your TV and sound system.”

With all this in mind, I recommend keeping it simple (like any of this is simple): Your Roku Ultra streams content (video and audio) into your Dolby Atmos receiver or soundbar, which in turn passes video to your TV. It’s true that your ‘Smart TV’ is now just a dumb monitor, but that’s the way I would do it.

Which other streaming devices support Dolby Atmos?

The Roku Ultra I already mentioned. These also support Dolby Atmos:

  • Roku Streaming Stick+, Roku Express+
  • Amazon Fire TV Stick 4K, Fire TV Cube (gen 2), Fire TV (gen 3)
  • Nvidia Shield TV
  • Apple TV 4K (both gens)
  • Xbox One

Except there’s a catch: Not all video streaming services with Dolby Atmos content are compatible with all devices. For instance, while many newer Roku devices support Dolby Atmos, they can’t currently source it from Netflix or Amazon Prime Video, whereas the Apple TV 4K supports Dolby Atmos on both services, among others.

And to confuse things further, not all devices send Dolby Atmos the same way. For example, the Apple TV 4K sends Dolby Atmos streaming content via LPCM, which requires decoding from your TV before it can be sent along. That said, widespread Dolby Atmos compatibility is still very much a work in progress.

Once again, HDMI eARC may be your friend here. As long as both your TV and audio device support it, you should be able to source Dolby Atmos from all your compatible devices.

And finally, what is Dolby Atmos Music?

Streaming services that offer access to music mixed for Dolby Atmos include Tidal, Apple Music, and Amazon Music Unlimited. These require a subscription to the applicable tier that supports Dolby Music streams. And Dolby Atmos music will generally require a full speaker setup to properly appreciate. And while some Atmos soundbars and systems will allow for what’s called upmixing to Dolby Atmos (using algorithms to create a Dolby Atmos mix from a surround or stereo mix), it’s not recommended as it can drastically changes how things sound, usually for the worse.

That said, for those willing to take the plunge, Dolby Atmos Music can be an incredible experience that, in some ways, is even more impressive than Dolby Atmos for films and TV shows.

Credits: Thanks to Lee Neikirk, John Higgins, and Ryan Waniata for their great article entitled ‘WHAT IS DOLBY ATMOS, AND HOW DO YOU GET IT?‘. Now I know a lot more about this topic than I did before reading their article.

** update **

Below is a response to a customer regarding simplifying their entertainment system. Currently they use a laptop and Roku to deliver content to their TV. My objective is to remove both the laptop and the Roku, while improving the audio experience.

Here are a few ideas:

1) Consider going with an LG Smart TV that supports WebOS. This gives you access to a Web Browser on the TV which could eliminate the need for the PC for content. (video)

2) Use a wireless keyword to access the TV browser (source)

3) Connect your LG TV to your sound system*

In theory, this configuration removes both the laptop and the Roku from the equation. Also, you might not have to give up on your Dolby Visio/Dolby Atmos quest. It appears LG OLED TVs support this as well. (video) and supports a Dolby Atmos-capable soundbar.

I need to do a bit more research on how the Atmos soundbar connects to the OLED TV (HDMI or optical?), Then if you want to keep your current sound system in the mix as well, maybe we can use an optical splitter? (*This video only answers part of the question) But perhaps, since the soundbar is HDMI, then you still might have optical out that can connect to the existing stereo receiver. In that case, you would select the appropriate audio output from the TV to switch between sound bar and stereo. 

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